Two-wavelength wrinkling patterns in helicoidal plywood surfaces: imprinting energy landscapes onto geometric landscapes

We present a model to investigate the formation of two-length scale surface patterns in biological and synthetic anisotropic soft matter materials through the high order interaction of anisotropic interfacial tension and capillarity at their free surfaces. The unique pattern-formation mechanism emerging from the presented model is based on the interaction between lower and higher order anchoring modes. Analytical and numerical solutions are used to shed light on why and how simple anisotropic anchoring generates two-lengthscale wrinkles whose amplitudes are given in terms of anchoring coefficients. The novel finding is that the surface energy landscape with its maxima and minima can be imprinted onto the surface geometric landscape. Symmetry relations and scaling laws are used to provide the explicit relations between the anchoring constants and surface profile of the two length scale wrinkles. These new findings establish a new paradigm for characterizing surface wrinkling in biological liquid crystals, and inspire the design of novel functional surface structures.

Multiple-wavelength surface patterns in models of biological chiral liquid crystal membranes

We present a model to investigate the formation of surface patterns in biological materials through the interaction of anisotropic interfacial tension, bending elasticity, and capillarity at their free surfaces. Focusing on the cholesteric liquid crystal (CLC) material model, the generalized shape equation for anisotropic interfaces using the Rapini-Papoular anchoring and Helfrich free energies is applied to understand the formation of multi-length scale patterns, such as those found in floral petals. The chiral liquid crystal-membrane model is shown to be analogous to a driven pendulum, a connection that enables generic pattern classification as a function of bending elasticity, liquid crystal chirality and anchoring strength. The unique pattern-formation mechanism emerging from the model here presented is based on the nonlinear interaction between bending-driven folding and anchoring-driven creasing. The predictions are shown to capture accurately the two-scale wrinkling of certain tulips. These new findings enable not only to establish a new paradigm for characterizing surface wrinkling in biological liquid crystals, but also to inspire the design of functional surface structures.

Mimicking disruption of brain-immune system-joint communication results in collagen type II-induced arthritis in non-susceptible PVG rats

The brain-immune system-joint communication is disrupted during collagen type II (CII) arthritis in DA rats. Since PVG rats are not susceptible to arthritis induction, comparison of hypothalamic and peripheral neuro-endocrine and immune responses between immunized DA and PVG rats might help to explain their different susceptibility to develop the disease. PVG and DA rats were immunized with CII. Corticosterone, neurotransmitters, anti-CII antibodies, and cytokine concentrations in plasma, and hypothalamic neurotransmitters and cytokines were determined by ELISA, Luminex, HPLC and RT-qPCR. Adrenalectomy or sham-operation was performed in PVG and DA rats 14 days before immunization. Basal plasma corticosterone and adrenaline concentrations were significantly higher, and plasma cytokines and hypothalamic noradrenaline were lower in PVG rats than in DA rats. While DA rats developed severe arthritis upon immunization (maximum score 16), only 12 out of 28 PVG rats showed minimal symptoms (score 1-2). The density of sympathetic nerve fibers in arthritic joints of DA rats markedly decreased, but it remained stable in immunized PVG rats. The ratio corticosterone to IL-1β levels in plasma was markedly higher in immunized PVG rats than in arthritic DA rats. Adrenalectomy resulted in severe arthritis in PVG rats upon immunization with CII. While DA rats show an altered immune-brain communication that favors the development of arthritis, PVG rats express a protective neuro-endocrine milieu, particularly linked to the basal tone of the HPA axis. Mimicking disruption of this axis elicits arthritis in non-susceptible PVG rats.

The sympathetic nervous system modulates CD4(+)Foxp3(+) regulatory T cells via noradrenaline-dependent apoptosis in a murine model of lymphoproliferative disease

The sympathetic nervous system (SNS) plays a crucial role in the course and development of autoimmune disease in Fas-deficient lpr/lpr mice. As regulatory T cells (Tregs) are considered important modulators of autoimmune processes, we analyzed the interaction between the SNS and Tregs in this murine model of lymphoproliferative disease. We found that the percentage of Tregs among CD4(+) T cells is increased in the spleen, lymph nodes, and thymus of lpr/lpr mice as compared to age-matched C57Bl/6J (B6) mice. Furthermore, noradrenaline (NA), the main sympathetic neurotransmitter, induced apoptosis in B6- and lpr/lpr-derived Tregs. NA also reduced the frequency of Foxp3(+) cells and Foxp3 mRNA expression via β2-adrenoceptor (β2-AR)-mediated mechanisms in a concentration and time-dependent manner. Destruction of peripheral sympathetic nerves by 6-hydroxydopamine significantly increased the percentage of Tregs in B6 control mice to an extent comparable to aged-matched lpr/lpr mice. The concentration of splenic NA negatively correlated with the frequency of CD4(+)Foxp3(+) Tregs. Additionally, 60days after sympathectomy, a partial recovery of NA concentrations led to Treg percentages comparable to those of intact, vehicle-treated controls. Immunohistochemical analysis of the spleen revealed localization of single Foxp3(+) Tregs in proximity to NA-producing nerve fibers, providing an interface between Tregs and the SNS. Taken together, our data suggest a relation between the degree of splenic sympathetic innervation and the size of the Treg compartment. While there are few examples of endogenous substances capable of affecting Tregs, our results provide a possible explanation of how the magnitude of the Treg compartment in the spleen can be regulated by the SNS.

A cytokine network involving brain-borne IL-1β, IL-1ra, IL-18, IL-6, and TNFα operates during long-term potentiation and learning

We have previously shown that long-term potentiation (LTP) induces hippocampal IL-1β and IL-6 over-expression, and interfering their signalling either inhibits or supports, respectively, LTP maintenance. Consistently, blockade of endogenous IL-1 or IL-6 restricts or favours hippocampal-dependent memory, effects that were confirmed in genetically manipulated mice. Since cytokines are known for their high degree of mutual crosstalk, here we studied whether a network of cytokines with known neuromodulatory actions is activated during LTP and learning. We found that, besides IL-1β and IL-6, also IL-1 receptor antagonist (IL-1ra) and IL-18, but not TNFα are over-expressed during LTP maintenance in freely moving rats. The increased expression of these cytokines is causally related to an increase in synaptic strength since it was abrogated when LTP was interfered by blockade of NMDA-glutamate receptors. Likewise, IL-1 and IL-6 were found to be over-expressed in defined regions of the hippocampus during learning a hippocampus-dependent task. However, during learning, changes in IL-18 were restricted to the dorsal hippocampus, and no differences in TNFα and IL1-ra expression were noticed in the hippocampus. Noticeably, IL-1ra transcripts were significantly reduced in the prefrontal cortex. The relation between cytokine expression and learning was causal because such changes were not observed in animals from a pseudo-trained group that was subject to the same manipulation but could not learn the task. Taken together with previous studies, we conclude that activation of a cytokine network in the brain is a physiologic relevant phenomenon not only for LTP maintenance but also for certain types of learning.

Tropisetron suppresses collagen synthesis in skin fibroblasts via α7 nicotinic acetylcholine receptor and attenuates fibrosis in a scleroderma mouse model

OBJECTIVE

There is increasing evidence that serotonin (5-hydroxytryptamine [5-HT]) and distinct 5-HT receptors are involved in the pathogenesis of systemic sclerosis. The aim of this study was to test the hypothesis that tropisetron, a routinely used antiemetic agent previously characterized as a 5-HT(3/4) receptor-modulating agent, can directly affect collagen synthesis in vitro and attenuate experimentally induced fibrosis in vivo.

METHODS

Functional in vitro studies were performed using human dermal fibroblasts (HDFs). Signal transduction studies included immunofluorescence analysis, Western immunoblotting, promoter reporter assays, cAMP/Ca(2+) measurements, and use of pharmacologic activators and inhibitors. Gene silencing was performed using small interfering RNA. Putative receptors of tropisetron were detected by semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunofluorescence. The murine model of bleomycin-induced scleroderma was used to assess the antifibrogenic and antifibrotic effects of tropisetron in vivo. Collagen expression in vitro, ex vivo, and in situ was determined by real-time RT-PCR analysis, Western immunoblotting, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunohistochemical analysis.

RESULTS

Tropisetron suppressed collagen synthesis induced by transforming growth factor β1 (TGFβ1). This effect was independent of 5-HT(3/4) receptor but was mediated via α7 nicotinic acetylcholine receptor (α7nAChR). Suppression of TGFβ1-induced collagen synthesis occurred via an unknown molecular mechanism not involving modulation of the Smad, cAMP, Akt, c-Jun, or MAPK pathway. In vivo, tropisetron not only prevented skin fibrosis but also reduced the collagen content in established dermal fibrosis induced by bleomycin.

CONCLUSION

Tropisetron directly reduces collagen synthesis in HDFs via an α7nAChR-dependent mechanism. The antifibrogenic and antifibrotic effects of this agent observed in a mouse model of bleomycin- induced scleroderma indicate the future potential of tropisetron in the treatment of fibrotic diseases such as scleroderma.

Different peripheral neuroendocrine responses to Trypanosoma cruzi infection in mice lacking adaptive immunity

Trypanosoma cruzi infection in mice triggers neuroendocrine responses that affect the course of the disease. To analyze the contribution of adaptive immunity to these responses, comparative studies between normal C57Bl/6J and recombinase activator gene 1 (RAG-1)-deficient mice, which lack mature B and T lymphocytes, were performed. There was no difference between both types of mice in basal body weight. Following infection, higher parasitemia, increased IL-1β and IL-6 blood levels, less marked changes in lymphoid organs weight, no cardiomegaly, and earlier mortality were observed in RAG-1-deficient, compared with normal mice. The response of the hypothalamus-pituitary-adrenal axis after infection occurred earlier and was more intense in RAG-1-deficient mice than in normal mice. Noradrenaline concentration and serotonergic metabolism in the spleen, lymph nodes, and heart differed between RAG-1-deficient and normal mice. Our studies indicate that the absence of adaptive immunity to T. cruzi influences the neuroendocrine response to the infection with this parasite.

Chronic neuropathic pain-like behavior and brain-borne IL-1β

Neuropathic pain in animals results in increased IL-1β expression in the damaged nerve, the dorsal root ganglia, and the spinal cord. Here, we discuss our results showing that this cytokine is also overexpressed at supraspinal brain regions, in particular in the contralateral side of the hippocampus and prefrontal cortex and in the brainstem, in rats with neuropathic pain-like behavior. We show that neuropathic pain degree and development depend on the specific nerve injury model and rat strain studied, and that there is a correlation between hippocampal IL-1β expression and tactile sensitivity. Furthermore, the correlations between hippocampal IL-1β and IL-1ra or IL-6 observed in control animals, are disrupted in rats with increased pain sensitivity. The lateralization of increased cytokine expression indicates that this alteration may reflect nociception. The potential functional consequences of increased IL-1β expression in the brain during neuropathic pain are discussed.

Chronic neuropathic pain-like behavior correlates with IL-1β expression and disrupts cytokine interactions in the hippocampus

We have proposed that neuropathic pain engages emotional learning, suggesting the involvement of the hippocampus. Because cytokines in the periphery contribute to induction and maintenance of neuropathic pain but might also participate centrally, we used 2 neuropathic pain models, chronic constriction injury (CCI) and spared nerve injury (SNI), to investigate the temporal profile of hippocampal cytokine gene expression in 2 rat strains that show different postinjury behavioral threshold sensitivities. SNI induced long-lasting allodynia in both strains, while CCI induced allodynia with time-dependent recovery in Sprague Dawley (SD) and no allodynia in Wistar Kyoto (WK) rats. In WK rats, only SNI induced sustained upregulation of hippocampal interleukin (IL)-1β, while IL-6 expression was transiently increased and no significant changes in IL-1ra expression were detected. Conversely, in SD rats, SNI resulted in sustained and robust increased hippocampal IL-1β expression, which was only transient in rats with CCI. In this strain, IL-6 expression was not affected in any of the 2 injury models and IL-1ra expression was significantly increased in rats with SNI or CCI at late phases. We found that the degree and development of neuropathic pain depend on the specific nerve injury model and rat strain; that hippocampal IL-1β mRNA levels correlate with neuropathic pain behavior; that, in contrast to sham-operated animals, there are no correlations between hippocampal IL-1β and IL-1ra or IL-6 in neuropathic rats; and that alterations in cytokine expression are restricted to the hippocampus contralateral to the injury side, again implying that the observed changes reflect nociception.

A multifaceted analysis of immune-endocrine-metabolic alterations in patients with pulmonary tuberculosis

Our study investigated the circulating levels of factors involved in immune-inflammatory-endocrine-metabolic responses in patients with tuberculosis with the aim of uncovering a relation between certain immune and hormonal patterns, their clinical status and in vitro immune response. The concentration of leptin, adiponectin, IL-6, IL-1β, ghrelin, C-reactive protein (CRP), cortisol and dehydroepiandrosterone (DHEA), and the in vitro immune response (lymphoproliferation and IFN-γ production) was evaluated in 53 patients with active untreated tuberculosis, 27 household contacts and 25 healthy controls, without significant age- or sex-related differences. Patients had a lower body mass index (BMI), reduced levels of leptin and DHEA, and increased concentrations of CRP, IL-6, cortisol, IL-1β and nearly significant adiponectin values than household contacts and controls. Within tuberculosis patients the BMI and leptin levels were positively correlated and decreased with increasing disease severity, whereas higher concentrations of IL-6, CRP, IL-1β, cortisol, and ghrelin were seen in cases with moderate to severe tuberculosis. Household contacts had lower DHEA and higher IL-6 levels than controls. Group classification by means of discriminant analysis and the k-nearest neighbor method showed that tuberculosis patients were clearly different from the other groups, having higher levels of CRP and lower DHEA concentration and BMI. Furthermore, plasma leptin levels were positively associated with the basal in vitro IFN-γ production and the ConA-driven proliferation of cells from tuberculosis patients. Present alterations in the communication between the neuro-endocrine and immune systems in tuberculosis may contribute to disease worsening.

The role of the sympathetic nervous system in the thymus in health and disease

The existence of a network of immunoneuroendocrine interactions that results in the reciprocal modulation of the classical functions of each system is well established at present. Most of the evidence derives from studies on secondary lymphoid organs, such as the spleen and lymph nodes. In this article, several aspects relevant to understand the role of the sympathetic nervous system in the establishment of these interactions in the thymus are discussed. At present, the sympathetic innervation of the thymus, the expression of adrenergic receptors in thymic cells, particularly of β-adrenergic receptors, and the effect of sympathetic neurotransmitters, although mainly derived from in vitro or pharmacological studies, seem to be relatively well studied. However, other aspects, such as the relevance that immune-sympathetic interactions at the thymic level may have for certain diseases, specially autoimmune or other diseases that primarily involve the activation of the immune system, as well as how the integration of sympathetic and hormonal signals at local levels may affect thymic functions, certainly deserve further investigation.

Lipopolysaccharide-induced experimental immune activation does not impair memory functions in humans

Systemic immune activation occurring together with release of peripheral cytokines can affect behavior and the functioning of the central nervous system (CNS). However, it remains unknown whether and to what extent cognitive functions like memory and attention are affected during transient immune activation. We employed a human endotoxemia model and standardized neuropsychological tests to assess the cognitive effects of an experimental inflammation in two groups of 12 healthy young men before and after intravenous injection of lipopolysaccharide (LPS, Escherichia coli, 0.4 ng/kg) or physiological saline. Endotoxin administration caused a profound transient physiological response with elevations in body temperature, number of circulating neutrophils, and increases in plasma cytokine levels [interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α], and concentrations of norepinephrine, ACTH and cortisol. However, these changes in immune and neuroendocrine parameters were not associated with alterations of memory performance, selective attention or executive functions.

Re-exposure to endotoxin induces differential cytokine gene expression in the rat hypothalamus and spleen

This study was designed to investigate whether the pattern of hypothalamic and splenic cytokine expression induced by peripheral administration of a bacterial lipopolysaccharide (LPS) is affected by prior exposure to LPS derived from another bacterial strain. Injection of LPS from Salmonella enteritidis (LPS(2)) alone resulted in increased hypothalamic gene expression of IL-1beta, IL-6, TNFalpha, IL-1ra and IL-10. However, pre-exposure to LPS derived from Escherichia coli (LPS(1)) 3 weeks before, significantly attenuated hypothalamic IL-1ra, IL-6 and IL-10 expression. IL-1beta expression also tended to be lower. This pattern contrasted with the robust cytokine expression in the spleen of LPS(2)-treated rats previously exposed to LPS(1), since pre-treatment with endotoxin resulted in a significantly greater response of IL-1beta and IL-1ra to LPS(2). Expression of TNFalpha and IL-10 also tended to be higher. Pre-treatment with LPS(1) did not significantly affect the marked increase in corticosterone and adrenaline blood levels induced by LPS(2). Thus, while endotoxin pre-exposure seemed not to induce a "tolerant" state in the periphery as judged by the immune and endocrine parameters evaluated upon re-stimulation, expression of four of the six cytokines measured was decreased in the hypothalamus. This is the first demonstration that endotoxin priming can differentially affect cytokine expression in the central nervous system and peripheral tissues when a host is confronted with a second, acute, pro-inflammatory stimulus. These results may provide new evidence for the involvement of cytokine pathways in the central nervous system in modulating peripheral inflammation and mediating cognitive and behavioural alterations during inflammatory diseases.

Time-dependent alterations of peripheral immune parameters after nigrostriatal dopamine depletion in a rat model of Parkinson's disease

Dysfunction of the central dopaminergic system is associated with neurodegenerative disorders and mental illnesses such as Parkinson's disease and schizophrenia. Patients suffering from these diseases were reported to exhibit altered immune functions compared to healthy subjects and imbalance of the central dopaminergic system has been suggested as one causative factor for the immune disturbances. However, it is unclear whether the observed immune changes are primary or secondary to the disease. Here we demonstrate that central dopamine (DA) depletion in a rat model of Parkinson's disease induced transient changes in blood leukocyte distribution and cytokine production that were apparent until four weeks after bilateral intrastriatal administration of the neurotoxin 6-hydroxydopamine (6-OHDA). Eight weeks after treatment, no differences in blood immune parameters were anymore evident between neurotoxin-treated and control animals. Nevertheless, animals with a widespread damage of dopaminergic neurons in the nigrostriatal system showed an exacerbated pro-inflammatory response following in vivo challenge with bacterial lipopolysaccharide. Our data indicate that peripheral immune perturbations in the early phase after intrastriatal 6-OHDA administration might have been related to the neurodegenerative process itself whereas the increased sensitivity to the inflammatory stimulus seems to have resulted from an impaired dopaminergic control of prolactin (PRL) and corticosterone (CORT) secretion. The findings demonstrate that the brain dopaminergic system is involved in peripheral immune regulation and suggest that central dopaminergic hypoactivity bears the risk of excessive inflammation, e.g., during infection or tissue injury.

Immunoendocrine alterations during human tuberculosis as an integrated view of disease pathology

Tuberculosis (TB) is a chronic infectious disease accompanied by excessive and/or prolonged cytokine production, which might affect the immunoendocrine communication and favor the establishment of an adverse state with important alterations in essential biological functions. Studies in blood from TB patients showed increased levels of interferon gamma (IFN-gamma), interleukin 10 (IL-10), and IL-6, accompanied by a modest increase in the levels of cortisol, prolactin, and thyroid hormones and markedly augmented concentrations of growth hormone. Conversely, testosterone and dehydroepiandrosterone (DHEA) levels were profoundly decreased, resulting in an increased cortisol/DHEA ratio. The finding that culture supernatants from Mycobacterium-tuberculosis-stimulated peripheral blood mononuclear cells (PBMCs) of TB patients inhibit DHEA secretion by a human adrenal cell line indicates that immune cells from these patients can directly affect the synthesis of this hormone. Supporting the existence of bidirectional interactions, in vitro treatment of PBMCs from TB patients with physiological concentrations of cortisol inhibited mycobacterial antigen-driven lymphoproliferation and IFN-gamma production, whereas DHEA suppressed transforming growth factor beta production from cases with progressive disease. Further analysis showed that plasma DHEA levels correlated positively with the in vitroproduction of IFN-gamma by mycobacterial-stimulated PBMCs, and the cortisol/DHEA ratio was inversely correlated with IFN-gamma production. Lastly, it was also shown that the immunoendocrine imbalance in TB patients was associated with weight loss, which in turn correlated with the impairment on their specific in vitro cellular immune responses. These immunoendocrine interactions may play a detrimental role during TB, in terms of the development of protective immune responses, control of tissue damage and metabolic disorders, being implicated in disease aggravation and the 'classic' TB consumption.

Sympathetic nervous system-immune interactions in autoimmune lymphoproliferative diseases

With some exceptions, the sympathetic nervous system has often been regarded as an immunosuppressive system. However, we know now that the immunoregulatory role of the sympathetic nervous system cannot be described in such absolute terms. Indeed, sympathetic neurotransmitters can inhibit or stimulate an immune response depending on numerous variables, which include the type of adrenergic receptor involved, the kind of antigen that triggers the immune response, and the subset of immune cells affected. A most important consideration is that immune and sympathetic responses are phasic phenomena and the step of the immune response at which lymphoid and/or accessory cells are exposed to neurotransmitters, or deprived from their presence, seems decisive for the outcome. The large amount of basic research on the role that the sympathetic nervous system plays in neuroimmunomodulation has prompted studies on its pathological implications. Systemic lupus erythematosus is an autoimmune lymphoproliferative disease that has mainly been associated with a Th2 shift and increased humoral responses. Lpr/lpr mice, which express a defective Fas, are commonly used as a model of this disease, and more recently, also of the autoimmune lymphoproliferative syndrome. We have found that, besides defects in the Fas pathway, lpr/lpr mice have an altered sympathetic innervation, and that this alteration contributes to the pathogenesis of the disease. The results strongly support the hypothesis that the sympathetic nervous system can modulate the expression of autoimmune lymphoproliferative diseases.

Impaired immune responses in tuberculosis patients are related to weight loss that coexists with an immunoendocrine imbalance

The study's objective was to examine whether factors related to the host status may bear some relation with the profile of the immune response displayed by tuberculosis (TB) patients. The in vitro immune response (antigen-driven lymphoproliferation and cytokine production) and the presence of alcoholism or disease-related factors, like heart and respiratory rates, and weight loss (body mass index, BMI) were investigated in 31 males with active, untreated TB. Compared to 16 age-matched healthy males, TB patients presented depressed lymphoproliferation and increased IL-10 and TGF-beta production. Multivariate analysis indicated that most differences were no longer significant when controlling for the BMI. Immune and endocrine changes coexisting with weight loss, such as circulating levels of TNF-alpha, IFN-gamma, IL-6, cortisol, dehydroepiandrosterone and thyroid hormones, were also analyzed. While pairwise correlations between serum levels of IFN-gamma, T3 or T4 and BMI were not significant, BMI was negatively correlated with IL-6 levels (p < 0.025). In turn, levels of IL-6 correlated positively with cortisol concentrations (p <0.001). Stepwise regression analysis demonstrated that BMI was only associated with IL-6 (r = -0.423, R(2) = 0.18), with the difference remaining significant following adjustment for the other variables. As regards IL-6, BMI, cortisol and IFN-gamma could explain 74% of variability in IL-6 concentrations (R(2) = 0.74). No evidence for effect modification was shown when performing adjusted calculations. To conclude, the relation between weight loss and abnormal immune response of TB patients is partly associated with the immunoendocrine imbalance observed in parallel.

Central blockade of IL-1 does not impair taste-LPS associative learning

After saccharin intake is associated with the consequences of peripheral lipopolysaccharide (LPS) administration, rats develop a strong conditioned avoidance behavior against this gustatory stimulus. To investigate the role of central interleukin-1 (IL-1) as a key signal during taste-LPS engram formation, rats were chronically infused with IL-1 receptor antagonist into the lateral ventricle of the brain before, during and after a single association trial. The results indicate that a stable taste-LPS engram can be formed even under the chronic blockade of central IL-1 signaling during engram formation and consolidation. More importantly, our data show that animals which did not experience a fever response during association phase (due to the LPS encounter) were unable to elicit hyperthermia as part of the conditioned response. These data indicate that pairing a relevant taste stimulus with an immune challenge, such as LPS, might result in the formation of multiple engrams, specifically codifying independent information.

Murine taste-immune associative learning

Taste-immune associative learning can result from contingent pairings of an immune-competent unconditioned stimulus (US) with a gustative conditioned stimulus (CS). Recalling such an association may induce a set of physiological responses affecting behavior, endocrine, and immune functions. We have established a model of behaviorally conditioned immunosuppression employing the immunosuppressant drug cyclosporine A (CsA) as the US and saccharin as the CS in rats and humans. In order to investigate the inter-species generalization of this neuro-immune interaction, we tested the feasibility of this paradigm in mice. In a single-bottle scheme, male BALB/c mice (n=5) were conditioned by conducting three association trials and a single recall trial. Control groups (n=5/group) were designed to assure associative learning, pharmacological effects of the US, and placebo effect. Results show that CsA-conditioned animals displayed significant immunosuppression in the spleen after recall, measured by in vitro T-lymphocyte proliferation, and IL-2 production. However, the same animals did not show evidence of avoidance behavior to the CS. In contrast, evoking the association of saccharin-lithium chloride (inducing gastric malaise) in another set of animals (n=4/group) resulted in significant and pronounced avoidance of the taste (CS). These animals also displayed significant suppression of splenic T-lymphocyte responsiveness after the recall phase. The present results indicate that mice seem to be capable of associating a gustative stimulus with CsA, resulting in behaviorally conditioned immunosuppression without affecting appetitive behavior.

IL-1 resets glucose homeostasis at central levels

Administration of IL-1beta results in a profound and long-lasting hypoglycemia. Here, we show that this effect can be elicited by endogenous IL-1 and is related to not only the capacity of the cytokine to increase glucose uptake in peripheral tissues but also to mechanisms integrated in the brain. We show that (i) blockade of IL-1 receptors in the brain partially counteracted IL-1-induced hypoglycemia; (ii) peripheral administration or induction of IL-1 production resulted in IL-1beta gene expression in the hypothalamus of normal and insulin-resistant, leptin receptor-deficient, diabetic db/db mice; (iii) IL-1-treated normal and db/db mice challenged with glucose did not return to their initial glucose levels but remained hypoglycemic for several hours. This effect was largely antagonized by blockade of IL-1 receptors in the brain; and (iv) when animals with an advanced Type II diabetes were treated with IL-1 and challenged with glucose, they died in hypoglycemia. However, when IL-1 receptors in the brains of these diabetic mice were blocked, they survived, and glucose blood levels approached those that these mice had before IL-1 administration. The prolonged hypoglycemic effect of IL-1 is insulin-independent and develops against increased levels of glucocorticoids, catecholamines, and glucagon. These findings, together with the present demonstration that this effect is integrated in the brain and is paralleled by IL-1beta expression in the hypothalamus, indicate that this cytokine can reset glucose homeostasis at central levels. Such reset, along with the peripheral actions of the cytokine, would favor glucose uptake by immune cells during inflammatory/immune processes.

Knock-out mice reveal the contributions of P2Y and P2X receptors to nucleotide-induced Ca2+ signaling in macrophages

Immune cell function is modulated by changes in extracellular nucleotide levels. Here we used reverse transcription-PCR analyses, single cell Ca2+ imaging, and knock-out mice to define the receptors mediating nucleotide-induced Ca2+ signaling in resident peritoneal macrophages. In Ca2+-free buffer, the potent (K0.5<1 microm) stimulatory effect of UTP (or ATP) on endoplasmic reticulum (ER) Ca2+ release was abolished in cells isolated from P2Y2/P2Y4 double knock-out mice. Moreover, P2Y4(0/-), but not P2Y2-/-, macrophages responded to UTP. In P2Y2-/- macrophages, we could elicit Ca2+ responses to "pure" P2X receptor activation by applying ATP in buffer containing Ca2+. Purified UDP and ADP were ineffective agonists, although modest UDP-induced Ca2+ responses could be elicited in macrophages after "activation" with lipopolysaccharide and interferon-gamma. Notably, in Ca2+-free buffer, UTP-induced Ca2+ transients decayed within 1 min, and there was no response to repeated agonist challenge. Measurements of ER [Ca2+] with mag-fluo-4 showed that ER Ca2+ stores were depleted under these conditions. When extracellular Ca2+ was available, ER Ca2+ stores refilled, but Ca2+ increased to only approximately 40% of the initial value upon repeated UTP challenge. This apparent receptor desensitization persisted in GRK2+/- and GRK6-/- macrophages and after inhibition of candidate kinases protein kinase C and calmodulin-dependent kinase II. Initial challenge with UTP also reduced Ca2+ mobilization by complement component C5a (and vice versa). In conclusion, homologous receptor desensitization is not the major mechanism that rapidly dampens Ca2+ signaling mediated by P2Y2, the sole Gq-coupled receptor for UTP or ATP in macrophages. UDP responsiveness (P2Y6 receptor expression) increases following macrophage activation.

Expression of IL-1beta in supraspinal brain regions in rats with neuropathic pain

We examined mRNA expression of the pro-inflammatory cytokine IL-1beta in the brainstem, thalamus, and prefrontal cortex in two rat models of neuropathic pain. Rats received a neuropathic injury: spared nerve injury (SNI) or chronic constriction injury (CCI), sham injury, or were minimally handled (control). Neuropathic pain-like behavior was monitored by tracking tactile thresholds. SNI-injured animals showed a robust decrease in tactile thresholds of the injured foot, while CCI-injured animals did not show tactile threshold changes. Ten or 24 days after nerve injury, IL-1beta gene expression in the brain was determined by RT-PCR. IL-1beta expression changes were observed mainly at 10 days after injury in the SNI animals, contralateral to the injury side, with increased expression in the brainstem and prefrontal cortex. The results indicate that neuro-immune activation in neuropathic pain conditions includes supraspinal brain regions, suggesting cytokine modulation of supraspinal circuitry of pain in neuropathic conditions.

Electroviscous sphere–wall interactions

A theoretical analysis is presented to determine the forces of interaction between an electrically charged spherical particle and a charged plane wall when the particle translates parallel to the wall and rotates around its axis in a symmetric electrolyte solution at rest. The electroviscous effects, arising from the coupling between the electrical and hydrodynamic equations, are determined as a solution of three partial differential equations, derived from Cox's general theory [R.G. Cox, J. Fluid Mech. 338 (1997) 1], for electroviscous ion concentration, electroviscous potential and electroviscous flow field. It is a priori assumed that the double layer thickness surrounding each charged surfaces is much smaller than the particle size. Using the matched asymptotic expansion technique, the electroviscous forces experienced by the sphere are explicitly determined analytically for small particle-wall distances, but low and intermediate Peclet numbers.

Endogenous glucocorticoids cause thymus atrophy but are protective during acute Trypanosoma cruzi infection

The cytokine-mediated stimulation of the hypothalamus-pituitary-adrenal (HPA) axis is relevant for survival during bacterial endotoxemia and certain viral infections. However, only limited information is available regarding the effects of endogenous glucocorticoids on parasite diseases. We have studied this issue using, as a model, C57Bl/6 and Balb/c mice infected with Trypanosoma cruzi, the causal agent of Chagas' disease. These two mouse strains differ in the susceptibility to infection with the parasite. An intense stimulation of the HPA-axis was observed 3 weeks after infection in both strains, but glucocorticoid levels were already increased two- to threefold in the less susceptible Balb/c strain during the first week. Blockade of glucocorticoid receptors with the glucocorticoid antagonist RU486, starting on day 10 after infection, partially reversed the thymic atrophy and decreased the number of CD4(+)CD8(+) thymocytes without affecting parasitemia and the number of inflammatory foci in the heart. However, tumor necrosis factor-alpha blood levels were increased in infected mice of both strains treated with RU486. Furthermore, the blockade of glucocorticoid receptors accelerated death in C57Bl/6J mice and increased lethality to 100% in Balb/c mice. The results obtained represent the first evidence that an endocrine host response that is coupled to the immune process can strongly affect the course of a parasite infection.

The Role of Noradrenergic Nerves in the Development of the Lymphoproliferative Disease in Fas-Deficient, lpr/lpr Mice

Lpr/lpr mice develop a lymphoproliferative, autoimmune, lupus-like disease. These mice lack functional Fas (CD95) expression and are resistant to Fas ligand (CD178)-mediated apoptosis, a critical mechanism for the maintenance of peripheral tolerance. In this study, we show that noradrenaline (NA), the main sympathetic neurotransmitter, can induce apoptosis of lymphoid cells independently of functional Fas. Based on this finding, we used lpr/lpr mice as model to study the role of noradrenergic nerves in the expression of a lymphoproliferative disease. Early in ontogeny, the concentration of NA was significantly increased in the spleen of lpr/lpr mice, compared with normal littermates. However, splenic sympathetic innervation gradually declined as the disease progressed, and IgM blood levels and splenic NA concentration inversely correlated when the disease was overtly manifested. When the loss of noradrenergic fibers that occurred naturally during adult life in lpr/lpr mice was experimentally advanced by neonatal sympathectomy, the concentration of IgM and IgG2a in blood was markedly higher than that of control lpr/lpr mice, and the appearance of lymphadenopathy was accelerated. Furthermore, although neonatal denervation did not affect the life span of normal animals, it shortened significantly the survival time of lpr/lpr mice. These data show that, in addition to defects in the Fas pathway, an altered sympathetic innervation in lpr/lpr mice also contributes to the pathogenesis of the autoimmune disease, and strongly support the hypothesis that the sympathetic nervous system can modulate the expression of lymphoproliferative diseases.

Electroviscous cylinder–wall interactions

A theoretical analysis is presented to determine the forces of interaction between an electrically charged cylindrical particle and a charged plane boundary wall when the particle translates parallel to the wall and rotates around its axis in a symmetric electrolyte solution at rest. The electroviscous effects, arising from the coupling between the electrical and hydrodynamic equations, are determined as a solution of three partial differential equations, derived from R.G. Cox's general theory [J. Fluid Mech. 338 (1997) 1], for electroviscous ion concentration, electroviscous potential, and electroviscous flow field. It is assumed a priori that the double layer thickness surrounding each charged surface is much smaller than the length scale of the problem. Using the matched asymptotic expansion technique, the electroviscous forces experienced by the cylinder are explicitly determined analytically for small particle-wall distances for low and intermediate Peclet numbers. It is found that the tangential force usually increases the drag above the purely hydrodynamic drag, although for certain conditions the drag can be reduced. Similarly the normal force is usually repulsive, i.e., it is an electrokinetic lift force, but under certain conditions the normal force can be attractive.

Assessing flow alignment of nematic liquid crystals through linear viscoelasticity

Shear alignment of rodlike nematic liquid crystals is found when the reactive parameter lambda>1. Measurements of lambda usually require complex experiments. This paper presents a method based on the nematodynamic theory of Leslie and Ericksen that assesses flow alignment through small amplitude oscillatory flow. The method is based on the fact that the effect of lambda on the storage modulus G' of linear viscoelasticity, when the director is along the flow direction, is directly proportional to lambda-1. Thus the alignment-nonalignment transition for increasing lambda is a reentrant viscoelastic transition: viscoelastic (lambda<1) -->purely viscous (lambda=0) -->viscoelastic (lambda>1) that is reflected in the storage modulus G' and in the "loss angle" delta= tan(-1) (G"/G'). The methodology is demonstrated by analyzing the Leslie-Ericksen equations for small-amplitude oscillatory Poiseuille flow of (4-n-octyl- 4' -cyanobiphenyl) (8CB) using analytical and scaling methods. Since linear viscoelastic moduli are easily accessible, the proposed methodology is an additional useful and economical tool for nematodynamicists.

Microglial activation with atypical proinflammatory cytokine expression in a rat model of Parkinson's disease

Microglial activation has been associated with the pathogenesis of Parkinson's disease (PD). Among the many components of this reaction, cytokines have been proposed as candidates to mediate neurodegenerative or neuroprotective effects. We investigated the interleukin-1 system and tumour necrosis factor-alpha mRNA and protein levels at different time intervals in the subacute intrastriatal 6-hydroxydopamine rat model of PD, in parallel with the inflammatory response. Immunohistochemistry showed that microglial cells were activated from days 6-30 postlesion in the substantia nigra pars compacta. This microglial activation was accompanied by an atypical proinflammatory cytokine production: Interleukin-1alpha and beta mRNAs were found to be elevated 30 days post-6-hydroxydopamine injection (2- and 16-fold, respectively), but no induction for interleukin-1alpha or beta at the protein level was detected by ELISA. As a control, a classical proinflammatory stimulus, namely endotoxin, was capable of inducing these cytokines at similar mRNA levels but also at the protein level. In addition, tumour necrosis factor-alpha mRNA was hardly or not detected in the substantia nigra at any time point studied. Our data point out a tight control of key proinflammatory cytokine production in our model of PD. This work supports the notion that chronic neuronal death per se does not induce secretion of these proinflammatory cytokines but that an additional stimulus is necessary to stimulate proinflammatory cytokine production. The production of proinflammatory cytokines from "primed" microglia may in turn modulate disease progression as has been recently proposed in a model of prion disease.

c-Fos expression in the rat cerebral cortex during systemic GvH reaction

OBJECTIVE

It is becoming clear that the CNS receives signals from the peripheral immune system. In order to identify the areas of the brain that receive information about a specific immune response to allogeneic antigens, we studied the expression of c-Fos, a neural activation marker, in the cerebral cortex following the induction of a graft-vs.-host reaction (GvHR) in rats.

METHODS

C-Fos expression in the brain was studied by immunohistochemistry. GvHR was induced in (WKY x PVG)F(1) rats by injecting 5 x 10(8) spleen cells from PVG rats. Control rats received syngeneic cells.

RESULTS

No c-Fos immunoreactivity (IR) was observed in animals undergoing GvHR in the nucleus tractus solitarii (NTS), the locus coeruleus (LC), the organum vasculosum of lamina terminalis (OVLT), the paraventricular nucleus (PVN) or the central amygdaloid nucleus (Ce). In contrast, 3 days after GvH induction c-Fos IR was observed in the piriform cortex and several other olfactory-related regions indicating the stimulation of the olfactory pathway during GvHR. Strong c-Fos IR was also observed in the occipital visual cortex of animals undergoing a GvHR, suggesting that GvHR can affect visual functions. In addition, GvHR induced c-Fos IR in the prefrontal cortex (Cg3, orbital cortex), a region that has interconnections with most sensory modalities. Double-staining studies indicate that the cells that express the c-Fos signal are neurons.

CONCLUSION

We have defined the distribution of brain neurons that are affected during the induction phase of GvHR. Our results also indicate that the integration and processing of information from the immune system at CNS levels involve different areas during different types of immune responses.

Learning modulation by endogenous hippocampal IL-1: Blockade of endogenous IL-1 facilitates memory formation

The interleukin-1 (IL-1) cytokine family (IL-1alpha, IL-beta, and the IL-1 receptor antagonist) is involved in immune and inflammatory responses both in the brain and in the periphery. Recently, it has also been shown to influence behavior and memory consolidation. However, within the experimental systems studied, it has remained unclear whether the role of IL-1beta is associated solely with a pathophysiological process or whether it is a neuromodulator in normal adult brain. To evaluate the involvement of the nonpathological endogenous IL-1 system in learning, we studied the expression of IL-1alpha, IL-1beta, and IL-1ra during memory consolidation. We observed a learning-specific hippocampal IL-1alpha mRNA induction, but not that of IL-1beta or IL-1ra mRNAs, after inhibitory avoidance training. Moreover, when IL-1 receptor activity was inhibited using an adenoviral vector that expresses the IL-1 receptor antagonist (IL-1ra) in the hippocampus, both short-term and long-term memory retention scores were facilitated. In contrast, endogenous hippocampal IL-1 played no role in the habituation to a novel environment. These results demonstrate that endogenous hippocampal IL-1 specifically modulates a fear-motivated learning task, and suggest that IL-1alpha activity in the CNS is part of the hippocampal memory processing.

Monodomain and polydomain helicoids in chiral liquid-crystalline phases and their biological analogues

Many natural composites exhibit an architecture known as twisted plywood which imparts to them a superior set of physical properties. The origin of this structure is complex and not yet understood. However, it is thought to involve a lyotropic chiral nematic liquid-crystalline mesophase. Indeed, striking structural similarities have been observed and reported between biological fibrous composites and ordered fluids. In this work, a mathematical model based on the Landau-de Gennes theory has been developed to investigate the role played by constraining surfaces in the structural development of a composite material that experiences a liquid-crystalline state during the early steps of its morphogenesis. The goal of this study is to verify the need for an initial constraining surface in the formation of monodomain twisted plywoods as hypothesized by Neville (Tissue & Cell 20, 133 (1988); Biology of Fibrous Composites (Cambridge University Press, 1993)). The numerical simulations qualitatively confirm this theory and highlight the important role that modelling of liquid-crystalline self-assembly plays in the study of tissue morphogenesis.

Central catecholamine depletion inhibits peripheral lymphocyte responsiveness in spleen and blood

Experimental and clinical evidence has demonstrated extensive communication between the CNS and the immune system. To analyse the role of central catecholamines in modulating peripheral immune functions, we injected the neurotoxin 6-hydroxydopamine (6-OHDA) i.c.v. in rats. This treatment significantly reduced brain catecholamine content 2, 4 and 7 days after injection, and in the periphery splenic catecholamine levels were reduced 4 days after treatment. Central catecholamine depletion induced an inhibition of splenic and blood lymphocyte proliferation and splenic cytokine production and expression (interleukin-2 and interferon-gamma) 7 days after injection. In addition, central treatment with 6-OHDA reduced the percentage of spleen and peripheral blood natural killer (CD161 +) cells, and T-cytotoxic (CD8 +) cells in peripheral blood. The reduction in splenocyte proliferation was not associated with a glucocorticoid alteration but was completely abolished by prior peripheral sympathectomy. These data demonstrate a crucial role of central and peripheral catecholamines in modulating immune function.

Cyclophosphamide adjuvant arthritis in Trypanosoma cruzi infected rats with inflammatory cytokine effects

OBJECTIVE

To analyze whether the cyclophosphamide (CYC) induced reestablishment of adjuvant arthritis (AA) in chronically Trypanosoma cruzi infected rats correlates with changes in the secretion of pro- and antiinflammatory cytokines by popliteal lymph node cells.

METHODS

Inbred "l" rats infected with T. cruzi 90 days earlier and age matched controls were given CYC (25 mg/kg body weight) or physiologic saline 48 h before arthritis induction. Popliteal lymph node cells were collected at the time of AA induction (48 h after CYC treatment) or during the peak response, to study the concanavalin-A (ConA) or Mycobacterium tuberculosis-driven in vitro proliferation of several cytokines in their culture supernatants. Results. Infected rats given CYC were recovered from the otherwise decreased ConA induced proliferation seen at the time of peak AA. The CYC mediated reestablishment of AA in T. cruzi infected rats coexisted with an increased presence of tumor necrosis factor-a in supernatants from either antigen or ConA stimulated cultures as well as interleukin 12 (IL-12) in the latter case. CYC also lowered to normal the increased IL-10 levels from ConA stimulated cultures that the T. cruzi group displayed at the time of inducing AA. Conclusion. The process by which CYC restores the clinical expression of AA affects the balance between cytokines that influence the regulation of arthritis in favor of the inflammatory component.

Local and systemic autonomic nervous effects on cell migration to the spleen

This work is based on the hypothesis that sympathetic nerves regulate the uptake of circulating cells by the spleen by affecting splenic blood flow and that the quantity of cells sequestered depends on whether changes in noradrenergic transmission occur at local or systemic levels. Fluorescently labeled lymphoid cells were injected into rats, and organ blood flow was measured by the microsphere method. Increased retention of cells in the spleen paralleled by increased blood flow was detected after local denervation of this organ or administration of bacterial endotoxin. A comparable enhanced splenic blood flow was observed after general sympathectomy. However, the redistribution of blood perfusion during general vasodilatation resulted in deviation of leukocyte flow from the spleen, thus resulting in reduced uptake of cells by this organ. These results indicate that, although the uptake of cells by the spleen depends on arterial blood supply, enhanced perfusion does not always result in increased cell sequestration because general vasodilatation reduces cell uptake by this organ and even overrides stimulatory effects of endotoxin.

Temperature effects on capillary instabilities in a thin nematic liquid crystalline fiber embedded in a viscous matrix

Linear stability analysis of capillary instabilities in a thin nematic liquid crystalline cylindrical fiber embedded in an immiscible viscous matrix is performed by formulating and solving the governing nemato-capillary equations, that include the effect of temperature on the nematic ordering as well as the effect of the nematic orientation. A representative axial nematic orientation texture with the planar easy axis at the fiber surface is studied. The surface disturbance is expressed in normal modes, which include the azimuthal wave number m to take into account non-axisymmetric modes. Capillary instabilities in nematic fibers reflect the anisotropic nature of liquid crystals, such as the ordering and orientation contributions to the surface elasticity and surface normal and bending stresses. Surface gradients of normal and bending stresses provide additional anisotropic contributions to the capillary pressure that may renormalize the classical displacement and curvature forces that exist in any fluid fiber. The exact nature (stabilizing and destabilizing) and magnitude of the renormalization of the displacement and curvature forces depend on the nematic ordering and orientation, i.e. the anisotropic contribution to the surface energy, and accordingly capillary instabilities may be axisymmetric or non-axisymmetric. In addition, when the interface curvature effects are accounted for as contributions of the work of interfacial bending and torsion to the total energy of the system, the higher-order bending moment contribution to the surface stress tensor is critical in stabilizing the fiber instabilities. For the planar easy axis, the nematic ordering contribution to the surface energy, which renormalizes the effect of the fiber shape, plays a crucial role to determine the instability mechanisms. Moreover, the unstable modes, which are most likely observed, can be driven by the dependence of surface energy on the surface area. Low-ordering fibers display the classical axisymmetric mode, since the surface energy decreases by decreasing the surface area. Decreasing temperature gives rise to the encounter with a local maximum or to monotonic increase of the characteristic length of the axisymmetric mode. Meanwhile, in the presence of high surface ordering, non-axisymmetric finite wavelength instabilities emerge, with higher modes growing faster since the surface energy decreases by increasing the surface area. As temperature decreases, the pitches of the chiral microstructures become smaller. However, this non-axisymmetric instability mechanism can be regulated by taking account of the surface bending moment, which contains higher order variations in the interface curvatures. More and more non-axisymmetric modes emerge as temperature decreases, but, at constant temperature, only a finite number of non-axisymmetric modes are unstable and a single fastest growing mode emerges with lower and higher unstable modes growing slower. For nematic fibers, the classical fiber-to-droplet transformation is one of several possible instability pathways, while others include chiral microstructures. The capillary instabilities' growth rate of a thin nematic fiber in a viscous matrix is suppressed by increasing either the fiber or matrix viscosity, but the estimated droplet sizes after fiber breakup in axisymmetric instabilities decrease with increasing the matrix viscosity.

Involvement of noradrenergic nerves in the activation and clonal deletion of T cells stimulated by superantigen in vivo

Superantigens, like staphylococcal enterotoxin B (SEB), induce a strong proliferative response followed by clonal deletion of a substantial portion of defined Vbeta T cells. The remaining cells display in vitro anergy. We found that the immune response to SEB was paralleled by biphasic changes in the activity of the sympathetic nervous system. Furthermore, sympathetic denervation resulted in decreased SEB-induced cell proliferation and IL-2 production, and impeded the specific deletion of splenic CD4Vbeta8 cells observed in intact animals without affecting anergy. These studies provide the first evidence of an immunoregulatory cross-talk between sympathetic nerves and superantigen-activated immune cells.

Texture formation in carbonaceous mesophase fibers

Carbonaceous mesophases are discotic nematic liquid crystals that are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a wide range of different fiber textures. Planar polar (PP) and planar radial (PR) textures are two ubiquitous ones. This paper presents theory and simulation of the texture formation process using the Landau-de Gennes mesoscopic theory for discotic liquid crystals. The computed PP and PR textures phase diagram, given in terms of temperature and fiber radius, is presented to establish the processing conditions and geometric factors that lead to the selection of these textures. Thin fibers adopt the PR texture, while thicker fibers and higher temperatures adopt the PP texture. The influence of elastic anisotropy to the formation of textures and structure is thoroughly characterized.